In a thin film transistor-active matrix liquid crystal display (TFT-AMLCD) device or a TFT-active matrix organic light-emitting diode (TFT-AMOLED) device, a source 5 of a TFT is connected to a pixel electrode 6, so as to transmit a data signal to the pixel electrode 6, thereby enabling the device to normally display an image.
As shown in FIG. 1, in the TFT-AMLCD, each pixel unit includes, from bottom up, a gate 1, a gate insulation layer 2, an active layer 3 corresponding to the gate 1, the source 5 and a drain 4 that are located on a same layer and connected to each other by means of the active layer 3, and the pixel electrode 6 electrically connected to the source 5. After the drain 4 receives the data signal, the active layer 3, driven by the gate 1, activates the source 5 and the drain 4, so that the data signal to which the drain 4 is connected is transmitted to the pixel electrode 6 through the source 5. Therefore, good contact between the source 5 and the pixel electrode 6 is very important. In addition, a buffer layer 8 may be provided between the gate 1 and a base substrate 7.
As shown in FIG. 1, many products incorporate a polymer film on array 9 (PFA) in a manufacturing process of an array substrate. Specifically, the source 5 and the drain 4 are covered with a first insulation layer 10, and the PFA, formed after the formation of the first insulation layer 10, facilitates subsequent procedures of the array substrate.
During manufacture of the array substrate, after the PFA is formed, a common electrode 11 is formed on the PFA, and a second insulation layer 12 is formed on the common electrode 11, followed by formation of the pixel electrode 6 finally.
In order for the pixel electrode 6 located in an uppermost layer to be electrically connected to the source 5, it is necessary to provide a via hole 13 which penetrates the second insulation layer 12, the PFA, and the first insulation layer 10 in sequence from the top down, so that the source 5 is partially exposed to be electrically connected to the pixel electrode 6.
The PFA can react with a metal material of the source 5, to form a nonconductive substance. In the prior art, the via hole 13 is etched layer by layer, i.e., the first insulation layer 10 is etched after being formed, and the PFA is formed after formation of the via hole 13. Such being the case, the PFA can be brought into contact with a portion of the source 5 exposed by the via hole 13, to form a nonconductive substance on said portion of the source 5. This affects electrical connection between the source 5 and the pixel electrode 6 and lowers yield of the display device.